EP 0,540,051 and JP 06227971 describe a series of compounds useful as factor Xa inhibitors or to treat influenza based on the formula: ##STR2## wherein A is an alkylene linker optionally substituted by hydroxyalkyl, carboxyl, alkoxycarbonyl, alkoxycarbonylalkyl, or carboxyalkyl, X is a bond, O, S, or carbonyl, n is 0-4, and Y is an optionally substituted carbocycle or heterocycle. The present invention does not involve compounds containing the above noted combination of A, X, n, and Y.
Tidwell et al, Thrombosis Research 1981, 24, 73-83, describe factor Xa inhibitory activity of a series of aromatic mono- and di-amidines. The amidino aromatic moieties are include indole, indoline, benzofuran and benzimidazole.
Tidwell et al, J. Med. Chem. 1983, 26, 294-298, report a series of amidinoindoles of the formula: ##STR3## wherein one of R.sup.1 and R.sup.2 is amidine, X may be methyl or ethyl when Y and Z are H, Y may be C(O)CH.sub.2 CH.sub.3 when X and Z are H, and Z may be CHO, COCH.sub.3, COCF.sub.3, or C(O)Ph when X and Y are H. Thrombin inhibition constants are given for these compounds.
EP 0,655,439 discuss IIb/IIIa antagonists of the formula: ##STR4## wherein the core ring is a heterocycle, B is a basic group, A is an acidic group, R.sub.1 is an optional substituent, R.sub.2 is an optional substituent, and L.sub.a and L.sub.b are linkers which may optionally be substituted. The present invention does not contain the L.sub.a --A group.
Fairley et al, J. Med. Chem. 1993, 36, 1746-1753, illustrate a series of bis(amidinobenzimidazoles) and bis(amidinoindoles) of the formulae: ##STR5## wherein R is an amidine or derivative thereof and X is an alkylene, alkenylene, phenylene or phenylenedimethylene linker. The DNA binding capabilities of these compounds were studied and reported, but inhibition of trypsin-like enzymes was not discussed.
WO 95/08540 depicts bis(amidinobenzimidazolyl)alkanes of the formula: ##STR6## wherein Z is an amidine derivative and R and R.sup.1 are selected from a variety of substituents including hydroxyl, amino, and alkoxy. These compounds are said to be useful in the treatment of viruses, specifically HIV. No mention is made of Xa or thrombin inhibition.
Trypsin-like enzymes are a group of proteases which hydrolyzed peptide bonds at basic residues liberating either a C-terminal arginyl or lysyl residue. Among these are enzymes of the blood coagulation and fibrinolytic system required for hemostasis. They are Factors II, X, VII, IX, XII, kallikrein, tissue plasminogen activators, urokinase-like plasminogen activator, and plasmin. Elevated levels of proteolysis by these proteases can result in disease states. For example, consumptive coagulopathy, a condition marked by a decrease in the blood levels of enzymes of both the coagulation system, the fibrinolytic system and accompanying protease inhibitors is often fatal. More specifically, proteolysis by thrombin is required for blood clotting. Inhibition of thrombin results in an effective inhibitor of blood clotting. The importance of an effective inhibitor of thrombin is underscored by the observation that conventional anticoagulants such as heparin (and its complex with the protein inhibitor, antithrombin III) are ineffective in blocking arterial thrombosis associated with myocardial infarctions and other clotting disorders. However, a low molecular weight thrombin inhibitor, containing a different functionality, was effective in blocking arterial thrombosis (Hanson and Harker, Proc. Natl. Acad. Sci. U.S.A. 85, 3184 (1988).
Activated factor Xa, whose major practical role is the generation of thrombin by the limited proteolysis of prothrombin, holds a central position that links the intrinsic and extrinsic activation mechanisms in the final common pathway of blood coagulation. The generation of thrombin, the final serine protease in the pathway to generate a fibrin clot, from its precursor is amplified by formation of prothrombinase complex (factor Xa, factor V, Ca.sup.2+ and phospholipid). Since it is calculated that one molecule of factor Xa can generate 138 molecules of thrombin (Elodi, S., Varadi, K.: Optimization of conditions for the catalytic effect of the factor IXa-factor VIII Complex: Probable role of the complex in the amplification of blood coagulation. Thromb. Res. 1979, 15, 617-629), inhibition of factor Xa may be more efficient that inactivation of thrombin in interrupting the blood coagulation system.
Therefore, efficacious and specific inhibitors of factor Xa or thrombin are needed as potentially valuable therapeutic agents for the treatment of thromboembolic disorders. It is thus desirable to discover new thrombin or factor Xa inhibitors.